New studies of uranium biosorption by extracellular polymeric substances (EPSs) of <i>Aspergillus clavatus</i> , using isotherms, thermodynamics and kinetics

Abstract

Extracellular polymeric substances (EPSs) were first extracted from A. clavatus as a biosorbent suitably to be used for uranium sorption. Maximum sorption capacity was found to be 123.5 mg g−1 at pH 5.0 (optimum initial pH value) and EPSs dose 1 g L−1.The Langmuir equation successfully fits sorption isotherms. The uptake kinetics are effectively modelled using the pseudo-first order rate equation. Uptake equilibrium occurred within 20 min. The thermodynamic study shows that the biosorption process is spontaneous and endothermic. The interaction mechanism between the EPSs system and uranium (VI) ions was investigated by FTIR spectrometry, SEM and EDX analysis. The metal could be desorbed using 0.1 M HCl solution and the sorbent could be recycled for four sorption-desorption cycles. Finally, the EPSs sorbent was efficiently tested on acidic ore leachate. These results demonstrated that EPSs could be a promising alternative for U(VI) biosorption and removal from aqueous solution.